Numerical Analysis of Short-term Blackout Scenario in a Nuclear Fuel Storage Vault

In the present work, numerical simulation of airflow distributions and heat transfer in a nuclear fuel storage vault after suction blower failure is investigated. In the absence of suction pressure at the outlets, natural convection is the dominating mode of heat transfer inside the vault. Considering the inherently unsteady nature of the airflow in the enclosure, a full-scale simulation of the airflow inside the vault was investigated. The safety of the vault was analysed in terms of velocity and temperature distributions of air near the concrete walls after the failure of the suction blowers. Therefore, the velocity of air was gradually reduced and later became stable. The reduction in air circulation resulted in rise in temperature of fuels and concrete walls in the vault. The temperature of the fuel subassemblies and magazines increased at different rate after the failure of suction blowers. The temperature of air below the heat generating region gradually increased. Due to heat transfer through the concrete wall, the temperature of the air in the vicinity of the wall was reduced.